Planoobaph co



S. B. WILLIAMS 1n.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 27. ms.

Patented 0ct.14,1919.

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. :1. v THE COLUMBIA PLANMRAFH CO WASHINGTON, Il-C.

S. B. WILLIAMS, In.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV 27. 1916- Patented Oct. 14,1919.

5 SHEETS-SHEET 2.

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THE COLUMBIA PLANnam um Cm. WASHINGTON, D. c.

s. B. WILLIAMS, In. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED NOV- 27. 19").

Patented Oct. 14, 1919;

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S. B. WILLIAMS, In.

.TELEPHONE EXCHANGE SYSTEM.

APPLlGATlON FILED NOV. 27. l9l 6.

Patented 00t;14,1919.

5 SHEETS-SHEET 4.

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S. B. WILLIAMS, 11'. TELEPHQNE EXCHANGE SYSTEM.

APPLICATION FILED NOV. 27. l9l6- Patented 001. 14,1919.

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UNITED STATES PATENT OFFICE.

SAMUEL B. WILIiIAMS,-J1 0F BROOKLYNJNEW YORK, ASSIGNOR TOWESTERN'ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N; Y., A CQRPOR ATION OFNEW YORK.

. TELEPHONE-EXCHANGE; SYSTEM.

. Patented 0ot.14, 19 19.

Application'filed November 27,1916. seri l ma 133,701.

To all whom it may concern:

Be it known that I, SAMUEL B. WILLIAMS,

J12, a citizen of the United States, residing at Brooklyn, in the countyof Kings and State of New York, have invented certain new and usefulImprovements in Telephone- Exchange Systems, of which the follow ng is afull, clear, concise, and exact descrlption.

This invention relates to emergency apparatus for telephone exchangesystems.

The object of the invention is to safeguard the operation of suchsystems by providing means automatically responsive to any failure ofthe more important parts of the organization for indicating the natureand location of the trouble and also for operatlng devices to restorethe operativeness of the system. r

In the present instance the inventionus illustrated in connection withacall distributing system of the type in which apparatus isautomatically operated to dis tribute the calls from a large number ofsubscribers lines to the connecting c rcuits of a large number ofoperators positlons.

In thisspecific embodiment'the subscribers" lines may be divided intogroups of 500, and the calls that-originate in eachgroup of 500 linesmay be-extended to the connecting cord circuits of a number of operatorspositions by means of a plurality of finder circuits, each of thefinder'circuits having a' switch at one end for connecting with any oneof the 500 lines and a switch at the other end for connectingwithanycord circuit of any of the plurality of operators positions. Thecontrolling circuits over which any calling line of the groupappropriates to its own use anyone of the'finder circuits, and overwhich the appropriated finder circuit gains access to any of theoperators positions at the time available, are common to all of the linecircuits, finder circuits and operators positions which are thus inoperative relation with each other. It "therefore follows that anythingwhich causes a failure of these common controlling circuits and-theirassociated apparatus may tie up the calls from .500 lines. It is towardthe safeguarding of the operation of such a system with respect to thefailure of the apparatusand circuits common to a'large number of linesand interconnecting links that the present invention Broadly stated,this"-result}is accomplished by providing devices that respond. to anyalteration of the electrical condition of the common controllingcircuits,'or to any change in the operative condition of the commoncontrolling apparatus that continues for an interval longer than theinterval that such alterat ons or changespersist" in the normaloperation of the systemyor that isunaccom panied by such changes asoccur in the normal sequence of operation. In the normal operation ofthe system the various stages of the operation follow each other'atsubstantially definite time inter'va'lsi Byasso- 'ciating with thecontrolling circuit s and apparatus emergency devices each of which isset to respond'within a definite'interval after a certainstage of. theoperation is reached, this interval being somewhat in excess of thenormal intervalrequired for reaching the succeedin'gstage o'ffthe operation, and causin the succeeding stage 30f operationtobloc the operationof the de vice, the devlce' operates only in case abnormal conditionsarlse. 7 p

A speclfic embodiment of the invention in a' preferred form .isillustrated in the accompanying drawingsfin which Figures 1, 2, 3, 4 and5, when, arranged' side by side injthe inanner'indicated bythe/correspond;

ing lines that extend to the margins of the drawings, showdiagrammatically the application of the invention to a telephone systemof the call distributingitype.

As illustrated" in the drawing,lthe system is represented as comprisingtelephonellines extending from stations, as A and A, to stationaryterminals upona-il'ine finder" frame,

thesestationary *term'inalsbeing' adapted to be connected with by aplurality of line finder switches or elevators, as LF and LF'." Eachline has associated with it a line relay l2 and a cutoff relay 11, ande'achJof the groups of lines-V into a which the"wli ole munher of linesserved by theffind'er framear'e divided, has associated withit certaingroup wapparatus designated"IlG and LG'a The group apparatus isconnected through the medium of conductors 57 and "58 with: the startingapparatus, (see '2), which s common to all of the; groups and to the 165whole number of lines terminating upon the. line finder frame. Thecommonstarting ap;

paratus is connected-through the ,medium of V conductors" 25,26,127, 28and 29.with the apparatus of are group er fiaaa circuits F, F and Fassociated with the line finder switches or elevators, as LF and LF,which serve the whole group of lines. The finder circuits F F and Fterminate in cord selector switches or elevators, as CS and CS, andthrough the medium of these, operating under the control of theoperators selecting apparatus SF, the finder circuits are adapt ed tohave their connections extended to any one of the connecting cordcircuits which extend in conductors 85, '86, 8 7 and 88 to the variousoperators positions. The operators selecting apparatus SF common to theentire group of finder circuits is brought into cooperative relationwith the apparatus of the finder circuits throu h the medium of theconductors 70, 71, 72, T3, 74, 75 and 76. Each one of the connectingcord circuits oflthe group at each of the operators positions may beequipped generally as indicated in Fig. 5, and may terminate in a plug170 which in completing the connection, may be inserted in the multiplespring-jack 14. of a line extending to called subscribers station A Theconnecting cords of the. various operators positions have multipleconnection with different cord selector frames like that which includesthe cord selectors CS and CS, such multiple connectionsfor a second cordselector frame together with the common operators selecting apparatusfor that frame being indicated at SF. I

The apparatus and circuits for safeguarding and indicating failure inthe common circuits and apparatus that cofiperatively relate the lineswith the finder Y shown in F ig; 2 of the drawing. The apparatuscomprising the lamp 250, the relays 251, 252, 253 and 255 and the key254 (Fig. 2) has to do with the safeguarding of the common conductorswhich link the line group apparatus with the starting apparatus. Theapparatus comprising the lamp 260, the relays 26 1, 262, 255 and the key263 has to do with safeguarding thepart of the common, starting controlcircuit which passes through the resting contacts of the relays 22,23and 'to ground. The apparatus comprising the lamp 240, the relays 241,242, 24:3, 244 and 245 and the key 246 has todo with the safeguarding ofthe system with respect to -.the operation of the common startingrelay22 and the'coopen ating parts of the finder circuits. The apparatus comprising the lamps 270 and 271 and the relays 272, 273 and 281(see Fig. at) has to do with the safeguarding of the common circuitoverwhich the finder circuits are brought into operative relation with thecommon operators position selectmg apparatus, The apparatus comprisingthe lamps 280' and 271 and the relays 281, 282, 283, 287 and 285 has todo with the safeguard'ngof the releaseof the common circuits areoperators selecting apparatus. The lamps 290 and 291 and the relays 292,293 and 29a have to do with safeguarding the common circuit over whicheach operators position has operative relation with the correspondingposition-selecting apparatus of the different selector frames.

The line finder switches LF, LF, and the cord selector switches CS, US,may be sub stantiall y like the switch illustrated and described inPatent 1,177,044- to James L. Mc- Quarrie, issued March 28, 1916. Theline finder and cord selector switches are alike in all substantialrespects. Each comprises a longitudinally movable shaft l-carrying asmany sets of brushes 2 as there are groups of stationary terminals to beengaged. To move the shaft up, an extension at the lower end of theshaft is brought into engagement with the constantly rotating powermember 3 by means of an idler wheel operated by the updrive magnet 2;and to move the shaft down, the extension is brought into engagementwith the power member 4: by means of an idler wheel operated by thedown-drive magnet 62. Normally the brushes of each of the sets 2 areapart so as'to clear the associatedterminals by means of a separatingcam 5 lo-' cated between the innermost brushes of the .set. The cam 5 isrotatably mounted, and when rotated in one direction releases the.brushes and permits them to engage the associated terminals. Thetripping or releasing of the brushes is controlled by a number of tripmagnets, as 16' and 17. Each of these when energized rotates anassociated trip rod 6 that extends transversely to the shafts 1 andcarries as many trip yokes 7 as there are finder switches in the group.The trip rod in rotating brings all of its trip yokes 7 into position tooperate the brush-controlling cams 5 of the corresponding sets ofbrushes on. all of the sets, so that whichever of the finder switchesiscaused to move up has that set of brushes tripped that corre spondswith the particular trip magnet 16, 17, that is at the time energized.When the finder switch that has been in use is returned to its normalposition, any of the associated controlling cams 5 that has been trippedis engaged and rotated in a reverse direction to separate its switchsprings again and thus render them inactive. Each of the line finder andcord selector switches has associated with it a commutator 8 whichcomprises a number of stationary commutator segments and a set ofmovable brushes car ried at the top of the switch shaft 1 andcooperating with the stationary segi'imnts. This commutator serves tomake and break a number of the controlling circuits in the variousstages of the upwardmovement of the switch shaft. V

For controlling the circuits the organ ization, there areemployed' anumber ofse- 1- quence switches which are shown at different points andare designated 100, 200 and-300 V respectively. These sequence switchesmay be of the-type disclosed in Patent 1,127,808 issued February 9,1916to Reynolds and Baldwin. Each consists of an electromagneticallycontrolled motor or driving mechanism and a number of associated (switchcams. The witch cams associated with each of the sequence switches 100are designated 101 to 103, inclusive; those associated with each of thesequence switches 200 are designated 201 to-222, inclusive; andthoseassociated with each of the sequence switches 300 are designated 301 to304, inclusive. To each of the contacts associated with the varioussequence switch camsare appliedcertain numerals. These numerals in thecase of the cams 101, 201 and'301 :indicatethe only positions of theassociated sequence switch in which these particular contacts are open;the numerals applied to all'of the other-con-. tacts of each sequenceswitch indicate the only positions of the particular sequence switch inwhich the associated contacts-are closed. 1 w

The sequence switches 100 merely act as timing switches and have onlyone resting position. The resting positions ottheother sequenceswitches, andthe stages of operation with which these positions.areassociatedyare asfollows.

Sequence switch .200.

1. Normal.

2.. Awaiting starting circuit.

3. Awaiting starting circuit-release.

+1. Huntingcalling line.

6. Awaiting preceding finder circuit.

7. Awaiting operators selecting circuit. 8. Releasing operatorsselecting circuit.

a 9. Hunting cord circuit. I

14:. Talking. A

15. Line finder-at tell-'tal 16. Line finder return.

17. lord selector return.

Sequence switch 300.,

1. Awaiting a call. '4. Position vacant. 17. Position busy. 7

The operation cfithe system as illustrated in the accompanying drawingsis as follows:

' When a subscriber calls the taking of the telephone receiver from itshook 1 closes a circuit in the usualway that causes the energizationofthc associated lino relay at the central oflice. The line relay inopcrating closes a circuit that extends from battery through the windingof relay 19 of the group in which the calling line. located, contacts103 (1S+1-to 11..) or seouenc switch 1000f thatgroup. group conductor18-, and armature and front contact .of line relay 12 to ground. Relay19 in operating closes a circuit that extends from battery through theright-hand winding of relay 24:, front contact and armature of relay 19,conductor 57, inner back contact and'armature of relay 22,1eft-hand backcontact and armature of relay 23, back contact and armatureof relay toground. Relay 24 in operating closes a-loclgmg circuit for itself in itsleft-hand front contact and. armature, and in doing so causes theoperation of the associated tripping 'magnetylfi, the energizing pathfor thectri'pping magnet and for the left-hand or looking winding ofrelay 2 1 being in parallel from battery by way of the left-hand frontcontact and armature of relay 24, conductor 58, winding of relay 22,left-hand back contact andarmature of contact 102 (18?; 'to 1%), andrightghand front contact andgarmature of" relay 24 to ground. Theclosure of this. circuit moves 7 sequence switch out. of position 1,whereit completes its cycle andagain comes to rest in position 1. Whilethe sequence switch 100 is rotating it maintains open in sequence switchcontact 108 (-18% to 11;) the connection of the relay 19 with the groupconductor 18, so that'duringthis period the relay '19 is not'underthe'control of the-line relays'12 of-the corresponding group. Duringthis interval the callingfline is found and-the line relay 12de'energized torelnove the ground from the conductor 18, as here;inafter-to .be described. [1 j Included inithecircuityby'way of conductor f-58 closed upon theinitiation'of a call, as described above. isthe winding of.

the starting relay 22. This relay in operating closes the circuit of thestarting conductor-29, andin doing so brings about the movement ofa-vline. finder switch otjone or another of the finder circuits RF or F Forreasons that Jwill hereinafterbeen: plainejd only one ot'the,.'sequenceswitches ass sociated with these findercircuits is in;po. ;-:i-"

tion 2. Assuming-that this is the sequence switch ofifinder circu t F, acircuit is completed that extends. from batterv through the'lett-han'dwinding of relay 30. sequence switch contacts 206 (-2) ,conductor 29,inner front. contact and armature of relay 22; left- "from batterythrough resistance coilf56', so

quence switch contacts :21? (21to .9.) right hand wind ng oji relay 80,sequeuce switch 7 past the corresponding trip yokes.

contacts 216 (2 to 1) and (2 to 9), lefthand front contact and armatureof relay 30, and armature and back contact of relay 37 to ground. Relay30 also closes a circuit that extends from battery through the motormagnet and cam 202 (2) of sequence switch 200, right-hand front contactand armature of relay 30, sequence switch contacts 208 (18 to 14) and to7) to ground. The closure of this circuit causes sequence switch 200 tomove out of position 2 and come to rest in position 3.

In position 3 of the switch, a circuit is closed that extends frombattery by way of the up-drive magnet 3201 the corresponding line finderswitch LF, sequence switch contact 207 (3 to 4), front contact andrighthand armature of relay 30, and sequence switch contacts 208 (18 to1 1) and (2 to 7) to ground. The energization of the updrive magnet 32starts the upward move ment of the corresponding elevator rod with itsassociated sets of brushes. At the outset of the upward movement of theelevator rod all of the brush trip levers are mo%ed he only trip magnetthat is energized in this case is the magnet 16 which corresponds withthe group in which the calling line is assumed to be located; andconsequently the only trip yoke in position to engage a trip lever onthe elevator rod is the one which controls the brushes 40, 11, 4:2 and43 that are adapted to engage the terminals of that particular group oflines. This set of brushes therefore is released and made operative, andthe other sets are held clear of their associated line terminals.

As soon as the'set of brushes corresponding with the calling line istripped, the group apparatus, by means of which the lines control thebrush tripping and line finder starting operations, may be returned toits normal condition. The first step in this restoring operation iseffected by the closure of a circuit which is completed by way of the Ksegment of the line finder commutator immediately after the brushes aretripped. This circuit extends from battery in parallel branches throughthe relays 33 and 23 (see Fig. 2), conductor 26, sequence switch contact209 to 3), conductor 68, and to ground by way of the K segment of theline finder commutator and its associated brush. The energization of therelay 23 interrupts, in the left-hand back contact of that relay, thepreviously described circuit that has up to this time maintained theenergization of the trip magnet 16, the group relay 2 1 and the commonstarting relay 22. Relay 23 in its right-hand front contact closes alocking circuit for itself and the associated relay 33 that extends byway of conductor 25 and the sequence switch contacts 210 (2% to 1) ofall of the finder circuits in series, to ground at a point beyond thelast switch of the serles.

As has already been stated, normally there is only one of the findercircuits with its sequence switch in position 2 awaiting the receipt ofa call. When the call comes in this sequence switch is immediately moveding applies a ground to conductor 28 to move the sequence switch ofanother finder circuit out of position 1 and into position 2, and whichalso applies a ground to the condue tor 27 to move the sequence switchof the appropriated finder circuit out of position 3.

Assuming that the sequence switch of finder circuit F is in position 1,and that the sequence switch of finder circuit F is in some positionbetween sand 17, that finder circuit being assumed to be in use, theoperation of the relay 33 completes a circuit from battery through themotor magnet. and cont acts 203 (1) of the sequence switch of findercircuit F, contacts 211 (1) of the same sequence switch, contacts 211 (3to 17) and 1 to 17) of the sequence switch 200 of finder circuit Fcontacts 212 (3 to 17) and (3 to 33;) of the sequence switch 200 offinder circuit 'F that has just been appropriated, conductor 28, andleft-hand front contact and armature of relay 33 to ground. This causesthe sequence switch of finder circuit F to move into position 2. Atthesame time the sequence switch of finder circuit F is moved out ofposition 3 by the closure of a circuit that extends from battery throughthe motor magnet and contacts 203 (3) of the sequence switch of thatcircuit, conductor 27, and right-handfront contact and armature of relay33 to ground.

As soon as the sequence switch of finder circuit F moves into position2, it opens in its contacts 210 the circuit by way of con ductor 25which up to this moment has maintained relays 23 and 33 energized, andthese relays thereupon release their armatures. Relay 23 in releasingreconnects to ground the circuit which extends in branches 57 and 58through the various sets of line group relays, thus again giving theline groups access to the starting circuit.

At this stage of the operation of the system the sequence switch of theappropriated finder circuit F is in position 4, and the elevator of theassociated line finder LF is moving up with the set of brushes trippedthat corresponds with the group in which the calling line is located. Asthe tripped brushes rise they come" into engagement successively withthe sets of terminals corresponding with the different lines of thegroup. At the instant of engagement of the brush 42 with thecorresponding line terminal 46 of each line', a circuit is closed thatextends from battery by way of the relay 52, sequence switch contacts212 (2 to 4), con ductor 50, brush 42, line terminal 46, conductor 53,and winding of cutofi relay 11 to ground. In case a line over which thebrushes are passing is busy, either as a callingor as a called line, abranch pathfrom battery is closed to conductor 53 which serves to shuntthe relay 52 and prevent its operation as the finder brushes pass overthe terminals of the corresponding line. In the case of the lines thatare not busy, the relay 52 isoperated as the brushes engagethe'terminals of such lines. In attractinggits armatures the relay 52closes'a circuit that extends from battery through the lower winding ofthe relay 37, front contact and inner armature of relay 52, sequenceswitch contact 213 (2 to 4), conductor 49, brush 41, line terminal 45,conductor 39 to one limb of the telephone line, thence by way of thepath controlled in contacts of the substation switchhook to the otherlimb of the line, conductor 38, terminal 44, brush 40, conductor48,,sequence switch contact 214 (2 to 4), upperarmature and frontcontact of the relay 52, and upper windingof the relay '37 to ground.The circuit traced above is not completed until the finder switchbrushes engage the terminals of the calling line, for the reason thatthe calling line is the only line that has its telephone receiver offthe hook and at the same time is not made busy by being connected witheither by some other line finder or by a connecting cord calling plug.The completion of this circuit energizes the relay 37 and causes thatrelay to interrupt in its back contact the circuit by way oftheleft-hand armature and front contact of the'relay 30, sequence switchcontacts 216, right-hand winding of relay 30, sequence switch contacts217 and resistance 56 to battery, which circuit has been holding relay30 locked up from the moment that the relay was first energized upon thereceipt of the call.

Relay 30in releasing its armaturesbreaks its own locking circuit tracedabove, and also breaks the previously traced path including sequenceswitch contacts 208', right-hand front contacts of the relay 30, andsequence switch contacts 207, over which current has been flowing toenergize the up-drive magnet 32 of the line finder. Therefore theoperation of the relay 37 upon the finding of 30, sequenceswitch'contacts 208' (18 to 14) and (2 to 7), to ground. The closure ofthis circuit moves the sequence switch out of p0= sition 4. hen thesequence switch reaches position'l, it closes a path for the fioW ofcurrent through the cutoff relay 11 of the calling line by way ofresistance coil 64, sequence switch contact 212 (4}to 12%), conductor 50, brush 42, line terminal 46 and.

conductor 53. The fiow of current. in this path operates the cutoffrelay 11 to disconnect the line relay 12 from the circuit, and thatrelay in releasing its armature disconnects ground'trom thecommonconductor 18. The disconnection of ground from conductor 18 occursbefore the timing sequence switch lOO has completed its cycle ofrotation and reconnected conductor 18 with relay 19.

In the foregoing the normal operation of the system has been describedup to the time when the line finder switch of an unengaged findercircuit. completes connection'with a calling line. The operation of thepart of the system that comes into action when an emergency or abnormalcondition arises in the circuits and apparatus controlling theabove-described stages of operation will now be explained.

In order thatthe'calling lines may have control over the apparatus thatenergizes an idle finder circuit when any line calls, it is necessarythat there shall be. a normally continuous series circuitby way of theconductors 57 and 58 through the resting. contacts of the group relays19 and 24 of the various groups. As long as this condition existscircuits are completed which hold the relays 251 and 252 energized. Thecircuit for the relay 251' extends frombattery through the winding ofthat relay, thence 'by way of the conductor58 and the left-hand backcontact and armature of each of the group relays 24 in series, thewinding of the starting re lay 22, left-hand back contact and armatureof; relay 23, and right-hand back contact and armature of relay 65 toground. ,Thenormal energizing circuit .forthe relay 252extends frombattery through the 'windingfof that relay and thence-by way ofconductor 57 and the back contact and armature 0t each of the grouprelays 19, inner back contact and armature of starting relay '22,lefthand back contact and armature of relay 23, and right-hand backcontact and armature i so of relay to ground. The winding of each of therelays 251 and 252 is of high resistance,the high resistance of therelay 251 preventing the current normally permitted to flow through itfrom energizing the starting relay 22; but in each case the normalcurrent flow is sufficient to keep the relays 251 and 252 energized andtheir arinatures attracted. lVhen the energizing circuit of either ofthese relays is interrupted, the relay is denergized and closes acircuit, subject to certain conditions that will hereinafter be set.forth, which extends from battery through the winding of relay 253, theswitch contacts of whichever of the relays 251 and 252 has released itsarmature, and the right-hand back contact and armature of relay 255 toground. When this circuit is closed the relay 253 in its upper frontcontact and armature closes a locking circuit for, itself by way of therelease key 254:; and also closesthe circuit that extends from batterythrough the common relay 134, the lamp 250, righthand front contact andarmature of relay 253, left-hand back contact and armature of relay 262to ground. The closure of this circuit lights the lamp 250 and alsoenergizes the relay 13a which may close a circuit for operating theelectromagnet 136 to give an alarm or bring about other appropriateaction. When the illumination of the lamp 250 has been noted, or suchaction as is called for by the arising of the condition has been taken,the release key 254 is pressed to open the locking circuit and permitthe release of the relay 253.

The operation as described above wil1 result if either of the groupconductors 57 and 58 has its continuity interrupted by the arising ofany abnormal condition in the circuit. If, however, the interruption ofthe conductors 57 and 58 is caused by the operation of any of the setsof group relays 19 and 2% by the initiation of a call in the normaloperation of the system, such interruption is accompanied by theactuation of the starting relay 22 as already described. This relay inoperating closes a circuit that extends from battery through the windingof relay 151 and the outer front contact and armature of relay 22 toground. Relay 151 in operating closes a circuit that extends frombattery through the winding of relay 255, lefthand front contact andarmature of relay 151 to ground. Relay 255 in operatinginterrupts in itsright-hand back cone tact and armature the path over which the relay 253is energized when the switch contacts of either or both of the relays251 and are closed upon the interruption of the energizing circuits ofthese relays. The relays 251 and 252 are so constructed as to be slow inreleasing their armatures, as by providing the cores of the relays withcopper shells, and the relay 253 may similarly be constructed andadjusted so as to be slow in attracting its armatures. The result isthat in the normal operation of the system the relay 255 is operated toblock or prevent the operation of the lamp controlling relay 253 beforethe slow-releasing relays 251 and 252 effect the closure of their switchcontacts to permit it. But if the interruption of the continuity ofconductors 57 and 58 is a continuing accidental interruption, and notincident to the normal operation of the systems, such interruption isnot followed by the operation of the relay 22, the relay 255 is notoperated to prevent the energization of the relay 253, and that relayoper ates to light the lamp 250.

Further, to prevent the lamp 250 from being lighted in the normaloperation of the system, the blocking relay 255 is also energized by theoperation of the relay 23. When the relay 23 operates as a result of thestarting of the finder switch, as already described, it opens in itsleft-hand back contact and armature the path to ground of the conductors57 and 58. This releases the starting relay 22, and that relay inreleasing opens the energizing circuit of the relay 151, which in turnopens the path over which the relay 255 had theretofore been energized.But relay 23 in operating closes an alternative energizing path for therelay 255 which extends by way of the left-hand front contact andarmature of the relay 23 and the right-hand back contact and armature ofrelay 65 to ground. Therefore the relay is held operated to prevent theclosure of the energizing path for the relay 253, which energizing pathwould otherwise be closed on account of the de'c'nergization of therelays 251 and 252, due to the interruption of conductors 57 and 58.

Another condition that results in the release of the relays 251 and 252in the normal operation of the system is that in which a call isinitiated when all of the finder cir-- cuits that serve the group oflines in question are in use. Then this condition arises, a circuit iscompleted that extends from battery through the winding of relay 135,conductor 80, and sequence switch contacts (st to 17 of all of the busyfinder circuits in series, to; ground at the end of the series. Relay135 in operating closes the energizing c' suit of the relay 133, therelay 133 in op eratingcloses the energizing circuit of the relay 138,the last mentioned relay in operating closes the energizing circuit ofthe relay 139, and that relay in operating closes the energizing circuitof the relay 65. The relays of this train perform other functions withwhich the present invention is not concerned and which functions,therefore, are not here described.

When the relay 65 operates, it opens in its right-hand armature and backcontact the normal connection with ground of the group conductors 57 and58, this being for the purposeof preventing calling lines fromenergizing the starting relay 22 and therelay 24 and tri magnet 16 ofthe associated group, whennone of the finder circuits is incondition tobe used. The opening of the path to ground of the conductors 57 and 58permits the deenergization of the slow acting relays 251 and 252; butinasmuch as the opening'of the conductors 57 and 58 is one that isincident to the normal operation of the system,the relay 255 is operatedto open the circuit of the relay 253 controlled by the relays 251 and 252, and thus prevent the lighting of the emergency lamp 250. Theenergizing circuit of the relay 255 is from battery, through the windingof that relay, andto ground byway ofthe front contact and left-handarmature of the relay 65. Thus the relay 65, in preventing the operationof the starting apparatus, when all of the'finder circuits are busy,also blocks and prevents the display of the emergency lamp 250.

The emergency lamp 260 and its associated controlling relays are for thepurpose of indicating any accidental or improper opening in that part ofthe series group circuit that extends to ground by way of restingcontacts of the relays 22, 23 and 65. The path by way of these relaycontacts to ground normally short-circuits the winding of the highresistance relay261, When this short circuit is interrupted, the relay261 is energized by means of current that flows to its winding frombattery by way of the winding of the relay 252, conductor 57, and theresting contacts-of the relays 19 of the various groups. The relay 261in operating closes, subject to the control of relay 2 in a mannerhereinafter to be described, a circuit that extends from battery,through the winding of relay 262, armature and front contact of relay261, and left-hand back contact and armature of relay 255 to ground.Relay 262 in operating closes, by Way of its right-hand armature andfront contact, a locking circuit for itself that includes the normallyclosed contacts of'the release key 263. It also, closes a circuit thatextends from battery, through the winding of common relay 134, lamp 260,and upper front contact and armature of relay 262 to ground. The closureof this last mentioned circuit causes the illumination, of theeinergencylamp 260; and when appropriate action has beentaken in response to thelighting of the lamp, the. relay'262 may be released by operatingthe'release key 263. In order that the emergency lampy260 may not belighted when the, short circuit is removed from relay 261 asa'result ofthe normal operation of the system, the circuit is. so arranged thateither of the relays 22,

23 and 65, in operating to break this normal short-eircuiting path, alsocloses an energiz ing path for the relay 2'55, and the last mentionedrelay in operating opens in its lefthand armature and back contact theground connection of the lamp controlling relay 262. Thus, when thestarting relay is energized, it closes in its outer armature and frontcontact the energizing circuit of the relay 151,-and that relay closesin its lefthand armature and front contact the energizing circuit of therelay 255, which operates, as described, to prevent the relay 261 fromcausing the energization of the relay 262. Again, when relay 23 inoperating opens the normal short circuit of the relay 261-, it closes inits left-hand armature and front contact the energizing circuit of therelay 255. Again, when the relay in operating breaks theshort-circuiting path of the relay 261, it closes in its left-handarmature and front contact the energizing circuit for the relay 255. Butifthe ground connection of the group conductors-57 and 58 is brokenaccidentally or abnormally, the relay 255 is not operated, and theactuation of the relay 261 causes the lighting of the emergency lamp260.

' It will be noted that the left-hand armature of the relay 262 controlsin its back contact the energizing circuit of the emergency lamp250,-and con'trolsin its front contact the energizing circuit of theemergency lamp 260; Therefore, if the interruption of the series groupcircuit including the conductors 57 and 58 is in that part of thecircuit that extends through the resting contact of the relays 22, 23and 65, the energization of the relay 262 tolight the emergency lamp260. prevents the lighting of the emergency lamp 250 which wouldotherwise result from this same interruption; But ifthe break in theseries group circuit is in that part which extends through the con tactsof the group relays 19 and 21, the

relay 262 is not operated, and the emergency lamp 250;is thereforelighted. Thus, one

or. the other of .thelamps 250 and 260 is lighted to indicate in whichpart of the com- 'mon series group circuit the accidental interruptionexists. v r

As has hereinbefore' been described, the starting relay 22 is actuatedby a calling line to appropriatea finder circuit, and is released whenthe passing of the K segment, at the outset of the upward movement of.the 1inefincler.,sWitcl1, energizes-the relay 23. .As soon as thestarting relay 22 is operated, it closes a circuit thatextends frombattery, through the winding of relay 241, right-hand back contact andarmature of relay and outer front contact and a1 mature of'relay 22 toground. Relay 211 in operating closes a branch from battery of this samecircuit that includes the Winding of relay 2&2. Relay 242 in operatingcloses another branch from battery of this same circuit that includesthe winding of relay Relay 243 in operating closes a looking circuit foritself by way of it righthand front conta'ctand armature, and also, inthe back contact of its right-hand armature, opens the energizingcircuit of the relay 24:1. Relay 241, in releasing its armature, opensthe energizing path through the winding of the relay 24:2; and relay242, in releasing, closes a path that extends from battery through theWinding of relay 24:1, left-hand armature and front contact of relay 2&3(which is now locked up), back contact and armature of relay 212, and toground by way of the outer front contact and armature or starting relay22. The relays 211, and are so constructed and adj usted as to be slowin pulling up and slow in releasing. Consequently a considerable timeinterval el-apses after the actuation of the star-ting relay 22 beforethe energizing path of the relay 244: is completed by the pulling up ofthe relays 2-ll, 212, and 24:3 in series and the falling 'back of therelays 2 11 and 242. This interval is such that in the normal operationof the system, the starting relay is released by the passing of the Ksegment and the energization of relay 23 before the slow-acting train ofrelays have acted to bring about the closure of the energizing circuitof relay 244. But it the release of the starting relay 22 is undulydelayed, the relay 24% operates and closes in its left-hand armature andfront contact the energizing circuit of the relay This relay inoperating closes a locking circuit for itself by way of its armature andthe release key 246, and also closes a circuit that extends frombattery, through the winding of common relay 134C, emer gency lamp 210,switch spring and armature of relay 215, and normally closed contacts ofrelease key 216 to ground. The closure of this circuit'lights theemergency lamp, and when appropriate action has been taken the lamp maybe extinguished and the relay 215 released by pressing the release key246. V

The relay 244 in operating as a result of an unduly delayed release ofthe starting relay 22, also closes a circuit'that'maycause apparatus toact automatically to remedy the condition responsible for the delayedrelease of the starting relay. This result is obtained by causing relay244:, when it operates, to apply aground to the conductor 28 to move outof position 1 the sequence switch of another finder circuit in the samemanner as relay 33 acts to bring about this result in the normaloperation of the system, as hereinbefore described. Thus, if the de layin the release of the starting relay 22 has been due to the failure ofthe line finder elevator, as LF, of the appropriated finder circuit tomove up, the relay 244 responds to the abnormal condition and groundsconductor 28 to prepare another finder circuit for the use of thecalling line.

The stages of the operation that are next to be described have to dowith the selection by the a propriated finder circuit of an idleoperators position and the selection of an idle connecting cord on thatposition. When the finder sequence switch 200 reaches position 5, whichit does as a result of being moved out of position 4: by the finding ofthe calling line as hereinbeforle described, it closes a circuit thatextends from battery by way of the winding of relay 55 (see Fig. 41),conductor 71, and sequence switch contact 218 (5 to 8) to ground. Theoperation of the relay 55 applies ground tothe conductors 81 ex tendingto all of the operators positions to the connecting circuit terminals ofwhich the cord selector switch of the finder circuit has access. At eachof the positions where the operator is at her station and is inreadiness to receive a call, the associated relay 91 (see Fig. 5) isinert and the operators telephone sequence switch 300 is in its 1position.

If the operator is listening in on a cord, the switch 415 associatedwith that cord circuit is closed, in any suitable manner, and anenergizing circuit completed for relay 91. Likewise, if all of theconnecting cords of a particular operators position are in use, theentire series of switches 416, one of which is associated with eachconnecting cord-circuit, are closed and the relay 191 energized tocomplete an energizing circuit for the relay 91. In either case, theenergization of the relay '91 renders the operators positionunselectable. Furthermore, when the operator is away from. her station,the switch 122 is operated, in any usual or convenient manner, tocomplete a circuit that extends from battery, through the motor magnetand contact 303 (1 or 17) of the sequence switch 300, to ground by wayof the resting contact and left-hand switch spring of the switch 122.The closure of this circuit moves the sequence switch to position 4:, inwhich position sequence switch contact'30 l (1) is open, and theposition is consequently .unselectable. When the operator takes herstation, the levers of switch 122 are moved to the right, and a circuitis completed for the motor magnetof sequence switch 300 by way ofcontact 303 (4) and the alternate contact and right-hand switch lever ofswitch 122, which causes the sequence switch to move to position 1, itsnext resting position. In this position oit'the sequence switch theoperators position, sub

ject to the control of relay 91, is rendered selectable by the closureof sequence switch contact 304 (1). At each position where neit er therelay 91is'inert and the sequenceswitch 300 is in position 1, asdescribed, a circuit is closed that extends from battery, through thewinding of associated relay 92, armature and back contact of relay 91,sequence switch contact 304 (1), conductor 81, armature and left-handfront contact of relay 55, toground. The relay 92 of'each awaitingavailable position, therefore attracts its armature and closes a circuitthat extends from battery, through the front contact and armature of.relay 92, to the conductor 82', and thence to ground by way of thewindings of the relays77 at the various cord selector frames as SF'andSF.

The finder circuit sequence switch 200 does not stop in position 5, butcontinues its movement and comes to rest in position 6, Here it awaitsfthe closing of a circuit the completion of which is dependent upon thecondition of the other finder circuits of thea'ssociated group. Thiscircuit extends from battery, through the left-hand winding of the relay30, contact 219 (6)7of the appropriated finder circuit sequence switch,contacts 219 (9 to 4) of the sequence switches of the associated findercircuits preceding it in the series, conductor 76, outer armature andback contact of relay 54, and right-hand back contact and arma ture ofrelay 61 to ground. This circuit is open either in cam 219 of apreceding finder sequence switch 200 in the series or in contacts of therelays 54 or 61 as long as any other sequence switch of the series is inpositions 4 to'9. That is, it is open from the time the line finderswitch of any associated finder circuits finds a calling line until thecord finder switch of that circuit has moved far enough to trip thebrushes corresponding with the selected group thus completing theoperators selection; Not until this has occurred, will the above tracedclrcuit of the awaiting finder circuit be closed.

When this circuit is closed relay 30 attracts its armatures andcompletes a circuit that extends from battery, through the motor magnetand sequence switch contact 202 (6) of the sequenceswitch 200, frontcontact and right-hand armature of relay 30, and sequenceswitch contacts208 (18 to 14) and (2 to 7) to ground. The completion of thiscircuitmoves the finder sequence switch out of position 6. r v I When thefinder sequence switch reaches position 6%, it closes a circuit thatextends from battery, through the winding'of relay '54 (see Fig. 4),left-hand back contact and armature of relay 61, conductor: 73, andfinder sequence switch contact 218 (6 to 8) to ground. V I 7 Relay 54attracts its armatures'and completes a branch of the circuit justtraced, which extends from conductor 7 3 by way of the armature and backcontact of the relay 63, front contact and left-hand armature'of gizedin parallel with the relay Relay 93 in operating disconnects its ownenergizing winding and that of associated relay 94 from the previouslytraced path to battery by way of the left-hand back contact and armatureof the relay 95, and connects them in a path which extends from batteryby way conductor 84. This causes the relay 95 also of the Winding of therelay and to beenergized and' to interrupt in its lefthand armature andback contact the path by way of conductor 83 over which the relays 93and 94 were initially energized, and also to close a circuit thatextends from battery by wa of the motor magnet and contact 303 (1) o theoperators sequence switch, right hand front contact and armature ofrelay '95 and right-hand contact and lever of switch 122 to ground. Theclosure of this circuit moves the operators sequence switch throughposition 4, and to position 17, where it remains until its motor magnetis energized by the operation of switch 192 or of switch 122.

Relay 94 inoperating closes a circuit from battery, through the windingof the trip magnet 20 corresponding to the selected operators position,and to ground by way of; the right-hand armature and front contact ofthe relay 94. This relay also closes a circuit that'extends frombattery, through the winding of the relay 63 and the left-hand armatureand front contact of the relay 94 to' ground. The relay 63 in operatingcloses a branch that extends from the conductor 73 (grounded at contact218 (6% to 8) of the line finder sequence switch), through *the armatureandfront contact of relay 63, condu'ctor 72, sequence switch contact 220(7), I

and left-hand winding of relay 30 to battery. Relay 3O attracts itsarmatures and 12'0' closes a circuit that extends frombattery,

, anism oi the 1..

switch contacts 217 (2 to 9), right-hand winding of relay 30, sequenceswitch contacts 216 (7 to 9) and (2 to 9), front contact and left-handarmature of relay 30 and armature and back contact of relay 37 toground.

When the sequence switch reaches position 8, it closes a circuit thatstarts the upward movement of the brush carrying rod of the cordselector switch, this circuitextending from battery, through theup-drive magnet 3 1 of the cord selector, conductor 89, sequence switchContact 207 (8 to 9), right hand front contact and armature of relay 30,sequence switch contact 218 (8 to 9), and thence to ground. At theoutset of the upward movement or" the cord selector brush rod, thetripping levers of the various sets of brushes are broughtsimultaneously into operative position with respect to the correspondingtrip yokes, and that set of brushes is tripped and made operative whosetrip magnet is at the time energized. In the present instance, it may beassumed that this is the trip magnet 20 associated with the terminals ofthe group or' connection cord circuits extending to the Ooperatorsposition.

Innnediately after the set of brushes is tripped, the common operatorsselecting circuit is restored so as to be available for the use of othercord finder switches. This is eiiected through the medium ot' a circuitthat is completed by the grounding of the K segment of the cord findercommutator, this segment being so located as to be engaged by its brushimmediately after the tripping levers or the sets of brushes pass theassociated tripping yokes. The circuit referred to extends from battery,through the winding of the relay 61, conductor 7&, sequence switchcontact 221 (7% to 8), conductor 180, cord finder commutator segment Kand its corresponding brushto ground. Relay 61 in operating opens in itsleft-hand back contact the previously traced circuit by way of conductor73 which, up to this time, has been holding energized the relay 95 atthe 0 operators position and the relays 93 and 91 corresponding to thisposition on the cord finder frame. The release of the rela 9ideenergizes the corresponding trip magnet 20 and the common relay 63.The deenergi- Zation of the relay 93 re-stablishes, subject to the releeof relay 61, the control of other finder circuits er the brush-trippingmechcociated cord finder frame. Relay 61 in operating closes a lockingcircuit for itself by way of conductor 7 sequence switch contact 218(6%; to 8), and

thence to ground. It also completes a circuit that extends from batterythrough the motor in net and contact 205 (8) of the sequence stch 200,conductor 75, right hand nt contact and armature of relay 61 to ground;The closure of this circuit moves sequence switch 200 out of position 8.In moving out of position 8, the sequence switch opens its contacts 218to 8) and 221 (7%: to 8), thus dcenergizing relay 61 and again extendingconductor 73 to the relay 54 and the conductors over which the operatorsselection is effected. In closing its righthand back contact uponrelease, relay 61 also restores the continuity of conductor 7 6 andmakes it availabl for moving out of position 6 the sequence switch ofsome other finder circuit which may be waiting for access to theoperators selecting circuit.

When the sequence switch 200 is moved out of position 8, it moves intoposition ,9 and there awaits the finding of an idle connecting cordcircuit upon the operators position that has been selected. 'As thebrush carrying rod moves up, the brushes 111, 112, 113 and 11 1 of theset that has been trippedcome into engagement with sets of terminals115, 116, 117 and 118 corresponding with the difi'erent'connecting cordcircuits located at that operators position. When a cord circuit is notin use, its corresponding terminal 118 is connected directly to ground;and when the terminals of such a connecting circuit are encountered, apath-is completed that extends from battery, through the lower windingof relay 87, sequence switch contacts 206 (8 to 9), conductor 99, brush114, terminal 118, conductor S8 of the cord circuit, contact 161, whichis closed when the associated cord is not in use, and back contact andarmature of relay 119 to ground. Current flowing in this circuit causesthe relay 37 to attract its armature and break the previously tracedcircuit by way of sequence switch contacts 216 and 217 and theright-hand winding of relay 30, which, up to this time, has been holdingrelay 30 energized. Then the relay 30 is released, it opens, in itsright-hand front contact, the previously traced circuit including theup-drive magnet 31, and thus causes the brushes of the cord finderswitch to come to rest on the terminals of the se-' lected cord circuit.The relay 30 in releasing also closes a circuit that extends frombattery through the motor magnet and con tact 202 (9) of the sequenceswitch 200, back contact and right hand armature of relay 50, andsequence switch contact 218 (8 to 9) ing which each of the findercircuits has operative relation with this common opera tors selectingcircuit is represented by the time that is occupied by the findersequence switch in moving from position l to posia tion 9. In the normaloperation of the system, this interval is short, bein merely the spaceof timerequired by the 1 nder circuit to test and obtain access tothe'common selecting circuit, select an idle operators position, operatethe brush trip magnet corre sponding with that position, and cause theupward movement of the brush-carrying elevator far enough to trip thecorresponding brushes. If for any reason this interval should be undulyprotracted, thus delaying the access of other finder circuits to theoperators selecting circuit, or if the operators selecting circuitshould accidentally become inoperative, apparatus is provided for givingprompt notification of such a operators selecting apparatus. Included inthe normally closed circuit is a relay 273 which is kept energized bythe normal current flow in this circuit. When the test circuit by way ofthe sequence switch contacts 219 (9 to 4:) is opened, this relay isdenergized, releases its armature and permits the closure of theassociated contacts. But the relay 273 is made slow-releasing, .asby providing its core with a copper sheath, so that the closure of theassociated contacts occurs a certain interval after the energizingcircuit is broken. When'the contacts of the relay 273 close, a circuitis' completed that extends'from' battery, through the lamp 27 0 and thelefthand winding of the relay 272 in parallel, andthence to ground byway of the switch contacts of therelay 273. The

completion of this circuit lights'the lamp 270 and also energizes therelay 272, which V attracts its armature and lights the lamp 271'.

In the normal operation of the system, the opening of the test circuitin the finder sequence switch contacts 219, when the sequence switchmoves out of'position at, is fol lowed promptly by the grounding ofconductor 73 byway of contacts 218 (6%; to 8) of the finder sequenceswitch when the sequence switch moves out of position 6 and connects thecorresponding finder circuit with the common operators selectingcircuit. The grounding of conductor 73 completes a circuit that extendsfrom battery, through the I ground.

winding of relay 281, conductor 73, and sequence switch contacts 218 to-8*) to Relay 281 thereupon, attracts its arn'iatures and closes acircuit that extends from battery, through'the winding of relay 273,left hand armature and front contact of relay281, and right-handarmature and front contact of relay 55, thelast mentioned 'made a littlelonger than the interval required in the normal operation of the systemfor the sequence switch to move to position 6% and energize relay 281.As a result,

the relay 281 normally acts to close the alternative energizing circuitfor the relay 273 before the relay 273 has had time to respond to theopening of its normal energizing circuit by way of conductor 70 and theseriesy I of sequence switch contacts 219. But if the opening of thecircuit by way of conductor 7.0 is not followed Within this definiteinterval by the closure of the alternative the finder se uence switchmoves into osi-.

tion-6 and operates relay 281, the relay 55 for any reason isnotenergized, then the alternative energizing circuit for relayr27 3 willnot be completed and the lamps 270 and 271 will be lighted to indicatetrouble in the circuit.

In the. normal operation of the system,

each finder circuit should have connection with the common operatorsselecting'circuit only for a sufficiently long interval to permit theselecting of an operators position,

the starting of the brush-carrying elevator and the tripping of thebrushes. The lamp 280 and its associated apparatus are vprovided toindicate when this normal interval is exceeded. At the moment any findercircuitis connected with the common operatorsselectmg apparatus throughthe medium of and 285. 1 As a result, the relay 282 operates andcloses-the energizing circuit for therelay 283, the relay 283 operatesand closes the'energizing circuit-for'the relay 284, the

relay 284 operates and closes the energizing, v

circuit for the relay 285, the relay 285lo'cks up and also opens theenergizing circuit of the relay 282, that relay releases slowly andopens the energizing circuit of the relay 283, the relay 283 releasesslowly and opens the energizing circuit of the relay 284, the relay 28%releases slowly and closes a circuit that extends from battery throughthe lamp 280 and from battery through the upper winding of relay 272 inparallel, left-hand,

armature and front contact of relay 285, back contact and armature ofrelay 28 1, and right-hand front contact and armature of relay 281 toground, thus lighting lamp 280, and operating relay 272 to light lamp271. The relays of the slow-acting train are organized and operate inthe manner disclosed in Patent 1,163,896 to Darrah, issued December 14,1915. The time intervals involved in the operation of this train ofrelays in order finally to close the circuit for the lamp 280 are, inthe aggregate, greater than the interval required for the findersequence switch to move from position 6% to position 8 in the normaloperation of the system. Therefore, if the system is operating normally,the relay 281 is deenergized and releases its armatures before thecircuit closed by way of its right-hand armature and front contact hasexisted long enough to effect the closure of the branch including thelamp 280 and the right-hand winding of the relay 27 2. But if, for anyreason, any finder circuit holds the common operators selecting circuitfor an unduly long interval, then the lamp 280, and the lamp 271,controlled by relay 272, are lighted to indicate the improper operationof the system.

The conductors 83 and 84, which lead to relay at each operatorsposition, are the paths over which is completed the selection of thecorresponding operators position by the common selecting apparatus ofthe different frames having access to that position. The operativenessof these paths and of the associated common apparatus is safeguarded bythe emergency apparatus involving the lamps 290 and 291 and the relays292, 293 and 294:. In the normal condition of the system, current flowsfrom battery by way of the winding of relay 95 at the operatorsposition,.conductor 84:, the left-hand armatures and back contacts ofthe relays 93 of the various frames in series, and the winding ofslow-releasing relay 292 to ground.

When the operators position is selected and this circuit broken by theoperation of the relay 93, as previously described, the relay 292 isdeenergized. As relay 292 is slow releasing, an interval elapses fromthe time it is deenergized until it permits the closure of itsassociated contacts. When these contacts .are closed, if the relay95 inthe meantime has not been energized, a circuit is completed that extendsfrom battery by way of the left-hand armature and back contact of relay95, conductor 83, switch contacts of relay 292 and winding of relay 293to ground. This causes relay 293 to attract its armature and close acircuit that extends from battery, through the winding of relay 294;,lamp 291 and front contact and armature of relay 293 to ground. He lay294; in attracting its armature closes an energizing circuit forlamp290. A set of relays 292 and 293 and a lamp 291 are pro vided inconnection with the conductors 83 and 84 associated with each operatorsposition. Only one set is shown in the drawing, the presence of theothers being understood. The relay 294; is of low resistance and iscommon to all of the lamps 291. The lamp 290 is a common lamp and lightsWhenever any of the lamps 291 is lighted.

The lighting of the lamp 291 occurs only when the circuit conditions areabnormal. In the normal operation of the system, the breaking of theenergizing circuit of the relay 292 is accompanied by the energizing ofthe operators position relay 95, and the last mentioned relay inoperating breaks the con tinuity of conductor 83 over which current mustflow to energize relay 293. Therefore, before the slow-releasing relay292 can re lease its armature far enough to close the associated switchcontacts, the circuit for relay 293 is broken at contacts of the relay9'5.

The relays involved in the emergency circuit part of the organizationmay be given such resistance values as are convenient, or as readilysuggest themselves to those skilled in the art. It may be stated,however, that the following have been found to be suitable resistancevalues for certain of the relaysz'relays 251 and 252, 1500 ohms; relay261, 3200 ohms; relay 22, 23.; ohms; relay 273, 1000 ohms; relay 281,2000 ohms; relay 292, 1500 ohms; relay 95, 23!; ohms; relay 293, 2000ohms; relay 29 1, 0. 15 ohms. The foregoing values are with a 8-voltcurrent supply for the parts of the circuit organization in which theserelays are included.

It has been found desirable to provide switches, preferably inassociation with the emergency signal lamps, for cutting out apparatusthat the lamps indicate is operating improperly, and for substitutingtherefor duplicate groups of apparatus in order to restore service. Theswitch 310, comprising switch contacts 3101 to 3106, inclusive, and theswitch 311, comprising switch contacts 3111 to 31111, inclusive, aresuch switches. One of the switches 310 is associated with the groupapparatus of each group of lines terminating upon a line finder frame,anda switch 311 is associated with the apparatus common to each linefinder frame. fW-hen the lighting of a lamp 250 indicates an impropercondition of the series group circuits, the switch 310, associated withthe group in which the trouble has occurred, may be operated, and inbeing operated disconnect-s the group apparatus consisting of the relays19 and 24 and the timing sequence switch 100 of thatiparticular groupand substitutes for it in the circuit a duplicate set of apparatus. Onlyone duplicate or emergency set of group apparatus is provided for theline finder frame, this set being connected 'with the alternate contactsof all of the switches 810 in the same manner in which the regularlyused setis connected with the resting switch contacts, and beingsubstituted by the throwing of'the associated switch 310,

-thrownf Similar switches for disconnecting the various groups ofapparatus in the operators selecting c1rcu1t may be provided to beoperated in response to the lighting of the cal the

lamps 271 and 280. Where desired, such vcorrective action may beefiected automaticallv. asin the operation of the relay 244 to renderanother finder ,circuit available in case the selected finder circuitfails to start its line finder switch, as previously described.

In order to complete the disclosure of the system connection with whichthe invention in its preferred form is here shown, the circuits andoperations involved in completing connection with the called line and indisestablishing connection at the end of the conversation will now bedescribed.

The connecting circuit to which'the finder circuit is extended in themanner hereinbetore described, is illustrated in thepresent instance asbeing a cord-circuit terminating in a connecting plug 170 and includingin its talking conductors 85 and 86 the windings of a repeating'coil 169with a bridged battery, and the usual signal controlling relays 171 and187. The connectingcircuit also includes a ringing key 120 by means 0:which current from the ringing generator 181 may be applied to thecircuit of the called line, and a listening key 130'by means 01 whichthe connection oft-he operators telephone set-14? with the called linemay be controlled. 7 V

The extension of the finder circuit to the connecting cordbriiurs about,in a manner which need not be described, the actuation of a signal ontheassociated operators position which informs the operator that a calliswaiting. Th'eoperators telephone is connected with the circuit bymeans of the listening key 130; and when the operator has learned thenumber of theline with which "pletes the connectionby inserting the pluginto the spring-jaclr14 t line. Before the plu'g'is'iniserted, a busytest may be made in the usual way over the path that is shownextendingfrom the tip of tee plug by way ofthe arn'ia-ture andiback contactof therelay 175, When the plug is inserted, a circuit is closedthat extendsfrom battery through the winding of the relay 119, winding of the relay175, the cotiperating sleeve contacts of the calling plug 170 andspring-Jack 14, and the wind ng of the cut-off relay 11 to ground. Thecompletion of this circuit causes all three relays to; at-

tract their armatures, the relay 119 opening the path to ground ofconductor 88, thus renderlng the connectlng. cord clrcuit un-'selectable, relay 175 disconnecting the tip of the plug'170irom the testconductor and completing the talking circuit of the tip strand, and thecutoif relay 11 disconnecting I the line relay 12 of the calledsubscribers" line. Ringing current from the ringing generator 181 may,then be appliedto the called subscribers'line by closing the. contactsof the ringing key 120. q

By means of appropriate, mechanism, which is disclosed in the patent toS. B.

Williams, Jr., No. 1,304,641, issued VMay 27,

1919, (application Serial No. 180,634, filed July'14, 1917), and whichit is unnecessary to describe as it forms no part of the presentinvention, the extension of the finder circuit to the connecting cordcircuit brings about the opening of the cont-acts of the switch 161 andthe closing of the contacts of the switch 152. The switch 152correspondsto the left-hand armature and'front contact ofrelay 152 of the abovementioned \Villiams patent, and theswitch 161 corresponds to cam 404 ofsequence switch 400 of the Williams patent.) The switch 161 in openingits contacts renders the associated cord-circuit unselectableimmediatelyand in advance of the opening of the contacts controlled bythe relay, 119. The'closing of the contacts of switch 152 completes a:circuit that extends from battery throughthewinding of relay 155, switchcontacts 152, conductor 87 contact 117 and cooperating brush 118 ofthecord selector, conductor 98, contacts 217 (9% to 14) and, (12 to 14)of the finder sequence switch, right-handwinding of relay 30, sequenceswitch contact 212 (12% to 14), conductor50, brush 42 and contact 46 ofthe line finder, conductor 53 and winding of cutofi relay 11 of thecalling subscribers line to ground. The currentthat flows in thiscircuit keeps the relays 155, 30 and 11 energized during the time thatthe connection is established. The relay 155 closes a normal break inthe ring strand 86 of the talking circuit. The relay 30, as long as itis energized, prevents the finder sequence switch 200 from movingout ofits talking positionv 14. The cutoff relay keeps the nected' from t ecalling line.

At the termination of the conversation, the replacing of the telephonereceivers on their switchhooks at the calling and called subscribersstations brings about the display of supervisory signals (not shown)which may be controlled by the cord-circuit relays 171 and 187 in theusual way, and the op erator in response to this indication withdrawsthe calling plug 170 from the spring iack of the called subscribersline. The withdrawal of the plug is accompanied by the opening of thecontacts of switch 152. This opens the circuit traced in the precedingparagraph including the relays 155, 30 and 11, and these relays releasetheir armatures. When relay 30 of the finder circuit releases, it closesa circuit that extends from battery through the motor magnet and contact202 (8 to 14) of the finder sequence switch, left-hand back contact andarmature of relay 30, and armature and back contact of relay 37 toground. This moves the finder sequence switch out of the talkingposition 14. IVhen the finder sequence switch reaches position 15, it ismoved through that position by means of a circuit that is completed frombattery, through its motor magnet and contact 202 (15), right-hand backcontact and armature of relay 30, sequence switch contacts 218 (15) toground. (hen the line finder sequence switch reaches position 16, acircuit is completed that extends from battery through the down-drivemagnet 62 of the line finder switch, and sequence switch contacts 208(16) to ground. As a result, the brushes of the line finder switch arereturned to normal.

When the brushes reach their normal position, a circuit is closed thatextends from battery, through the motor magnet and contact 205 (16) ofthe finder sequence switch, conductor 69, segment Y of the line findercommutator and its corresponding brush to ground. This moves the findersequence switch out of position 16. In the next resting position 17 ofthe finder sequence switch, a circuit is closed that extends frombattery through the down-drive magnet 35 of the cord selector switch,conductor 90, and sequence switch contact 218 (17) to ground. Theclosure of this circuit energizes the down-drive magnet 35 and causesthe cord selector brushes to return to their normal position. At the endof the downward movement of the brushes, a circuit is closed thatextends from battery through the motor magnet and contact 205 (17) ofthe finder sequence switch, conductor 31, Y segment of the cord selectorcommutator and corresponding brush to ground. The completion of thiscircuit moves the finder sequence switch 200 out of position 17 afterwhich it returns to position 1 under the control of its cam 201.

In order that the features to which this invention is directed may befully and clearly disclosed, it has been necessary to describe them inconnection with other features that are the subject of co-pendingapplications assigned to the same assignee, such applications includingthe application of S. B. Williams, Jr., Serial No. 75,328, filed January 31, 1916; application of S. B. Williams,

J12, Serial No. 75,329, filed January 31, 1916; application of S. B.Williams, Jr., Serial No. 107,090, filed July 1, 1916; joint applicationof S. B. Williams, Jr., and R. L. Quass, Serial No. 131,089, filedNovember 13, 1916; and application of F. A. Stearn, Serial No. 107 ,510, filed July 5, 1916. Such other features are the subject of claims inthe applications mentioned above, and are not claimed in the presentapplication.

What is claimed is:

1. In a call distributing system, the combination with a plurality oflines and a plurality of finder switches for making connectiontherewith, of a starting relay for starting the movement of a finderswitch to connect with a calling line, a controlling circuit for saidstarting relay, means responsive to the initiation of a call foraltering the electrical condition of said controlling circuit to operatesaid starting relay, an electrical emergency device, a timing device foroperating the same a predetermined interval after the electricalcondition of said controlling circuit is altered, and means forpreventing the operation of said emergency device made active in theoperation of said starting relay.

2. In a call distributing system, the combination with a plurality oflines and a finder switch for making connection therewith, of a startingrelay for said finder switch, an electrical emergency device, acontrolling circuit for said starting relay and said emergency device,means responsive to the initiation of a call for altering the electricalconditions of said controlling circuit to operate said starting relayfirst and said emergency device a predetermined interval thereafter, andmeans for preventing the operating of said emergency device madeoperative in the actuation of said starting relay.

3. In a telephone system, the combination with a plurality of lines anda finder switch for making connection therewith, of a starting relay forsaid finder switch, a controlling circuit for said starting relay, saidcontrolling circuit being normally continuous, an electrical emergencydevice responsive to an interruption in the continuity of saidcontrolling circuit a predetermined interval after said interruptionoccurs, means responsive to the initiation of a call for altering thenormal continuity of said controlling circuit and operating saidstarting re- 7 lay, and means for preventing the operation ing saidemergency device, and means for preventing the operation of saidemergency device made active, inv the starting of said finder switch.

5. In a telephone system, the combination with a plurality of lines anda plurality of finder switchesformaking connection there,- with, of anelectrical emergency device, means made active in initiating a call forfirst starting a finder switch and then after a predetermined intervaloperating said emergency device, and means for preventing the operationof said emergency device made active when all of said finder switchesare in use.

6. In a telephone system, theconrbination with 'a plurality of lines anda finder switch for making connection therewith, of a starting relay forsaid finder switch, .an electrical emergency device, means actuated inthe initiation of a call for operating said starting relay and thenafter a predetermined interval operating said emergency device, andmeans for preventing the operation of said emergency device made activein the starting of said finder switch.

7. In a switching system, the combination with a plurality ofcontrolling relays, ot a normally continuous controlling circuitextending serially through normally closed contacts of said relays, anemergency device, a controlling magnet therefor having its windingincluded in a shunt of said contacts and adapted to be operated when theportion of said controlling circuit including said contacts is opened,an electromagnet forpreventing the operation of said emergency de vice,and means for energizing said electroinagnet made operatlve intheoperation of any of said controlling relays, whereby said emergencydevice is responsive to abnormal opening of said controlling circuit butirresponsive to an opening efiected by the operation of said controllingrelays.

8. *In a telephone switching system, the combination with switchingapparatus, of a normally continuous controlling circuit therefor,normally closed contacts in one part of said circuit adapted to beopened in the switching I operations by group appa-- ratus, normallyclosed contacts included in another part of said controlling cirijuitadaptedto be opened in the switching operations by common apparatus, twoelectrical emergency devices, means responsive to the opening or saidcontrolling c1rcu1t associated wlth the group apparatus for operatingone of said devices, means responsive to the opening of the part of thecircuit associated with the common apparatus for operating the otherdevice, means responsive to the switching operations controlled by thegroup apparatus for preventing the operation of the first-mentionedemergency device, and b means responsive to the switching operationscontrolled by the common apparatus torpreventing the operation of thelast-mentioned emergency device, whereby an I abnormal opening of anypart of said controlling circuit is indicated by the operation of one orthe other of said emergency devices. 7

9. In a telephone system, the combination with a plurality of lines andaplurality of finder switches for making connection therewith,fof aswitchrfor controlling theoperative relation of said lines with saidfinder switches, an electrical emergency device, means made active byany line 1n calling 'for first operating said controlling switch formaking connection therewith, of a starting relay for said finder switch,means made active by any line in calling for operating said startingrelay, a slow-acting electrical emergency devlce, means made activeduring the operation of the starting relay for energizing said emergencydevice, and means made active in the starting of a finder switch forreleasing said starting relay be- -tore the expiration of the intervalrequired for the operation ofsaid emergency device.

11. In a telephone system thecombination with asplurality of lines and afinder switch for making connection therewith, of a starting relay forsaid switch actuated ,by a line in calling, means] made operative .in,the starting of said switch for releasing said starting relay, anemergency device, and

means for operating the same made effective by the energ zatlon of saidstartmg relay for longer than the normal interval required 'forstartmgsaid finder swltch.

'12-. In a telephone system, the combination with a plurality of linesand a plurality of finder. switches for making connection therewitlnof astarting circuit for said finder switches, a starting. relay under the

